Technical Field
The present disclosure relates to a digital refocusing system and a digital refocusing method. More particularly, the present disclosure relates to a block-based digital refocusing system and a block-based digital refocusing method.
Description of Related Art
With rapid development of digital cameras, the user can freely take desired images or videos. In order to highlight the main object, a shallow depth of field technique is usually used to produce the images with clear object and blurred background, so that the digital refocusing camera has become a new trend. In general, there are two ways to implement the digital refocusing camera. One is the commercial light field camera, such as Lytro or Raytrix. Another s the depth map produced by the computer vision method, wherein the depth map and the original picture are used to generate the shallow depth of field image, such as HTC M8 Duo Camera or Google Camera App.
One conventional shallow depth of field technique utilizes a ray-tracing method that is a three-dimensional rendering process of synthesizing data of a 3D object into an image observed at a given viewpoint of a camera. However, the computation of this ray-tracing method is too high to implement real-time refocusing. Another conventional shallow depth of field technique uses the light, field method with view interpolation to generate real-photo quality. However, the computation of this light field method is still too large to accomplish on portable devices. Further another conventional shallow depth of field technique utilizes an adaptive filter to generate the depth information that the blur kernel size is correlated with the depth value. Unfortunately, the adaptive filter will produce a discontinuity phenomenon in the foreground when the background is in focus. Yet another conventional shallow depth of field technique uses the layered depth map to perform hierarchical pictures. However, when the aperture is large, there is still a distorted phenomenon in the picture, wherein the apparent distortion will appear in large changes of the depth map. Therefore, a digital refocusing system and method having fast computation, real-time response and real-photo quality is commercially desirable.